A cell coverage indicates a range where communication between an evolved NodeB (eNodeB) and a User Equipment (UE) is valid in a wireless communication system. Thus, when the cell coverage is smaller than a reference coverage, that is, the cell coverage is downscaled, a problem occurs in communication between a cell transceiver in charge of a corresponding cell and the UE. Accordingly, there is a need for a method for accurately detecting whether the cell coverage is downscaled. Meanwhile, the reference coverage indicates a range of an area where the UE can receive a signal transmitted from the eNodeB when the eNodeB transmits the signal with the maximum strength.
In a conventional wireless communication system, a direct method or indirect method has been used to detect whether the cell coverage is downscaled.
The direct method checks a strength of a signal received by a UE from an eNodeB through a drive test and determines that a cell coverage is downscaled if the checked strength of the signal is lower than a preset threshold value.
The indirect method measures service qualities of UEs included in a particular cell and determines that a cell coverage is downscaled if the measured service quality is continuously lower than a preset threshold value.
However, when whether or not the cell coverage is downscaled is detected by using either the direct method or indirect method, the following problems occur:
First, the direct method cannot collect various data for a plurality of cells because exclusive manpower and equipment for the drive test are required. Generally, to check a state of a cell coverage of the entire mobile communication network, a time of several weeks through several months is required, increasing cost corresponding to the man power.
Moreover, when Radio Frequency (RF) setting of a cell is changed to adjust a cell coverage, the drive test has to be performed first on the cell to check if the adjusted cell coverage is valid. In this case, the aforementioned problems are also caused by the drive test.
The change of RF setting of a single cell also affects a wireless environment of an adjacent cell. As a result, when cell coverage adjustment is performed dynamically, the number of times the drive test is performed may increase sharply. Therefore, when the direct method is used, a scheme to minimize the number of times the drive test is performed is required.
In the meantime, the indirect method, because of using service qualities of UEs, may not accurately detect whether a cell coverage is downscaled. This is because the service qualities of the UEs may be degraded by several factors as well as the downscaling of the cell coverage and may be affected by a combination of various factors.
Moreover, since the service quality changes based on statistics corresponding to a periodic calculation result of a downlink error rate, a time for data collection is additionally required to reliably detect whether the cell coverage is downscaled. Accordingly, the indirect method cannot immediately handle a case where the cell coverage is downscaled.